This plugin hasnt been tested with the latest 3 major releases of WordPress. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.

WP PlusOne This

Description

This is a simple plugin without any hassles, it automatically adds the Google Plus One Button to your WordPress posts and pages.
There is no admin for this plugin since everything is done automatically, just upload the plugin , activate it and it will add the necessary code for the Google +1 Button to appear on every post and page.
The Button will be located at the Top-Right Corner Inline with your posts.

Features:

Automatically included on Posts

Automatically included on Pages

Button location is at the Top-Right Corner Inline With the Text

Simple enough, Does not slow down your site, Does not mess up other plugins

Screenshots

Plugin Activation

WP PlusOne This in Action

Installation

Install

Unzip the wp-plusone-this.zip file.

Upload the the wp-plusone-this folder to your wp-contents/plugins folder. If you’re using FTP, use ‘binary’ mode.